Phlebitis is a blood clot inside of a vein. These types of blood clots are not found very deep inside the body, and will not move to the lungs like deeper clots can.
Phlebitis can still cause pain in some patients, so treatment may be desired, as noted by the Cleveland Clinic. If the blood clot is causing severe pain and is blocking any circulation, surgery such as endoscopic vein removal may be needed to remove the clot to prevent further damage. Most of the time, the clot will go away on its own and does not require any special treatment.